Insulating structural board



May 23, 1939. A. H- TASHJIAN INSULATING 'STRUCTURAL BOARD Filed March l2, 1937 www www

INVENTOR.

ATTORN YQS` Patented May 23, 1939 UNITED STATES PATENT OFFICE Armen H. Tashjian, Cleveland, Ohio, assignor, by

mesne assignments, to William B. Miller, Lakewood, Ohio Application March 12, 1937, Serial No. 130,495

Claims.

This invention relates, as indicated, to insulating structural boards, but has reference more particularly to structural boards of laminated construction, designed especially for use as roof or oor slabs.

Standard insulating ber boards, such as Celotex, Masonite, Insulite, etc., have excellent insulating properties, but have relatively slight structural strength in flexure or bending under load, hence are not and cannot be used as structural slabs for load sustaining purposes, as roof or oor slabs, for example. If such boards could be made to have structural strength without appreciably reducing their insulating values,

their iield of application and use would be greatly increased.

A primary object of the invention, accordingly, is to provide an insulating structural board embodying standard insulating fiber boards of the aforesaid character, and having considerable structural strength and high insulating values.

A further object of the invention is to provide a structural board of the character described which is light in weight, so that it can be easily handled and transported; which can be cut and sawed with ordinary woodworking tools, and which can be readily secured in place in the same manner as lumber.

To the accomplishment of the foregoing and related ends, the invention then comprises the features hereinafter fully described, and particularly pointed out in the claims, the following description and the annexed drawing setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principle of the invention may be employed.

In said annexed drawing:

Fig. 1 is a plan view of a structural insulating tion;

Fig. 2 is a transverse cross-sectional view of the board, taken on the line 2-2 of Fig. l;

Fig. 3 is a fragmentary longitudinal cross-sectional view of the board on a substantially fullsize scale, taken on the line 3-3 of Fig. 1;

Fig. 4 is a view similar to Fig. 3, but showing the stitching extending through the entire thickness of the board;

Fig. 5 is a View similar to Fig. 3, but showing the use of doweling instead of stitching;

Fig. 6 is a view similar to Fig. 5, but showing the doweling extending through the entire thickness of the board;

Fig. 7 is a view similar to Fig. 5, but showing the use of pegging instead of doweling;

Fig. 8 is a View similar to Fig. 7, but showing the pegging extending through the entire thickness of the board;

Fig. 9 is a view similar to Fig. 8, but showing board embodying the novel features of the inventhe use of a hardenable composition for uniting the laminations of the structural board;

Fig. 10 is a perspective view of a row of nailer strips to which the structural boards are adapted to be secured; and

Fig. 11 is a fragmentary cross-sectional view of a construction embodying the structural boards.

Referring more particularly to Figs. 1, 2, 3 and 11 of the drawing, a laminated structural board embodying the principal features of the invention comprises a core I and covers or outer members 2 secured thereto. The core consists of a thick layer of loosely compacted libre board, such as is commonly available in the open market under various trade names, such, for example, as Celotex, Masonite, Insulitc", etc., such boards having in themselves excellent nsulating properties, but having relatively slight structural strength in flexure or bending under load. The thickness of the core, in general, is preferably about three-fourths of an inch to one inch. The cover or Outer laminations 2 are tough, hard ber boards which are also readily available in the open market under the trade-name Masonite Hardboard, and are preferably about one-fourth of an inch in thickness.

In making such a composite structure, the core I is run through a stitching machine using a strong tough fiber, such as sisal, to provide a plurality of rows of initially tensioned stitches 3, which extend through the core, the rows of stitches being parallel with each other or arranged in any desired pattern. Because the stitches do not pass through preformed holes, they have a strong frictional adherence to the core. When my stitched units are used as loadcarrying slabs and loaded, the stitching and its surface sections function to transmit the shear and diagonal tension stresses from the core to the covers.

The cover boards 2 are then applied under pressure to the upper and lower surfaces of the core l and are caused to adhere to such surfaces by means of a suitable water-proof cement, the cover boards projecting beyond the core at the side and at one end to thereby provide tongues 4 and 5 and grooves 6 and l, whereby interlocking of the boards in assembling a number of such boards to form a completed structure is facilitated.

The board, as thus manufactured, has a loadcarrying capacity far in excess of a similar board in which the core is not reinforced by stitching or similar means. The composite structure, both in theory and practice, is comparable to a symmetrica] structural welded I-beam, the top and bottom covers acting as the top and bottom flanges of such I-beam, the core acting as the web of such I-beam, and the cementitious layers uniting the covers with the core acting as the web welds of such I-beam. Intimate load tests- 'velop the ilange strength inherent in the hard fiber covers, and that the load-sustaining strength of the product could be increased if the core could be strengthened to better resist horizontal shear.'

Since themaximum horizontal shear of structural members in fiexure is at the neutral axis plane and iszero at the outermost ange bers, it was evident that the load value of any composite structure of the type described would be controlled by the horizontal shear-resisting value of the'ber core.

By providing a number of rows or other pattern arrangement of stitches having sections extendingv through the core in the manner described and with .the sections each performing a rivet-equivalent function, I am, in effect, providing a number of rows of fiber truss webbing through the core, thereby preventing horizontal shearing or horizontal sliding of fiber board layers over each other at all horizontal shear planes,

so that the'y horizontal shear resistance value of the core is materially increased and the maximum ilange'strength of the top and bottom covers is developed. In other words, a truly balf anced structural unit is secured, which can safely sustain greater loads with balanced internal Stresses.

Moreover, due to the fact that no metal is employed inthe construction of the structural unit' and that the threads or fiber used in making the stitches is of a non-metallic character,

4 undesirable heat v,conduction through the structure is. avoided and the insulation 4value of the structure is not appreciably diminished. Since the -iiatsexposed run length of the stitching on eitherside of the core are well embedded in the cement ywhich unites the cover boards with the core, and, are therefore well cemented to the covers, each and every stitch is xedly and rigidly, he1d tautly in place, acting as truss web members act in a truss.

As a result, even if the lfinished boards are sawed across the rows of stitches, the truss webbing will remain intact,

^ since the cut ends will still be firmly held in the cement.

To facilitate securing of the boards to joists or purlins ofsteel, I provide nailer strips 8 of treated wood, as shown in Fig. 10, each strip being approximately four feet in length and havl ing its ends cut at an angle and. parallel with and groovev ends of abutting boards assisting in forming vvtight-fitting joints. `In practice, the

.,joists may bespaced as much as four feet apart.

In that form ofthe invention shown in Fig. 4,

' the stitches I3 extend through the hard fiber boards` as well as through the core, so'that in additionto their providing the same sort of fiber 2,159,soo

truss webbing for shear resistance as hereinbefore described, the stitches mechanically secure the cover boards to the core. In this case, the stitching will be applied to the composite structure after the cover boards are cemented to the core.

In that form of the invention shown in Fig. 5, fiber or hard cork dowels or dowel pins I4 are employed and are driven through perforations in the core prior to cementing of the cover boards thereto. The dowels will be arranged in rows or in any desired pattern. These dowels function in the same manner as the stitching valready described to prevent the horizontal sliding of the fiber board fibers over each other and horizontal'shear planes. By making the dowels of fiber or cork, the insulating value of lthe finished product is left unaffected.

In Fig. 6, the dowel pins I5 of ber or hardcork extend through the covers 2, and the ends thereof are peaned to firmly secure the covers to the core.

In Fig. 7, fiber pegs I6 are driven through the core I, and in Fig. 8, the fiber pegs I1 extend through both covers as well as the core. In lieu of pegs, fiber staples may be employed.

1lik

In that form of the invention shown in Fig. 9, l

the core I is perforated at spaced intervals and the perforations are filled with a hardenable plastic composition, such for example, as an air curable rubber composition, designated I8, and upon pressing the cover boards against the core, some of the material in the perforations will be forced out of the ends of the perforations, spreading into the space between the core and cover boards and thereby assisting in the cementing of th covers to the clore.

By using sisal or similar fiber for the stitching, fiber or cork dowels, fiber pegs and staples or a non-metallic composition, such as shown in Fig. 9, undesirable heat conduction through the structure is avoided, and the product may be easily sawed along any line without danger of ruining saws or the necessity of pulling out the staples or nails before sawing or cutting, and may be easily tted and secured in place with ordinary woodworking tools. Furthermore, the use of brous or non-metallic materials as shearresistance members avoids any element which is likely to rust or corrode.

In actual tests, boards made as above described have shown remarkable load-sustaining ability, almost equivalent to that of reinforced concrete of equal thickness.

The cost of manufacture of the structural unit is low, so that the 'eld of application and use thereof is very wide', and, in particular, the product has been formed to be admirably adapted for use as roof or floor slabs.

Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the structure herein disclosed, provided the means stated by any ofthe following claims or the equivalent of such stated means be employed.

I therefore particularly point out and distinctly claim as my invention:

1. In a laminated structure of the character described, the combination of a middle lamina composed of aggregated insulating material without requisite load-carrying capacity, a pair of eri-- closing laminae possessing the requisite resistance to compression and tension stresses, kand means for reinforcing said middle lamina to provide a series of crossing attachments acting as a multi-rivet connection whereby to realize an increased resistance against shear stress to which said middle lamina is expectably to be subjected, said three laminae and reinforcing means being suitably severable and penetrable for appropriate sizing and attachment respectively.

2. A laminated unitary structure comprising a core of loosely compacted iibrous material, flexible and readily severable reinforcing means repeatedly extending entirely through and with strong frictional adherence to said core for the purpose of resisting horizontal shear, and outer laminations of closely compacted fibrous material for the purpose of resisting compression and tension stresses respectively, said outer laminations being secured to opposite sides of said core.

3. A structure of the character described comprising three severable laminae of which the separated pair are adequately hard and rigid for withstanding expectable compression and tension stresses and of which the interjacent one is of light weight insulating material inherently incapable of adequate shear resistance, a multitude of severable rivet-equivalent elements each extending entirely through said middle lamina and in predetermined proximity to each other to reinforce said middle lamina against shear stress and means for securing together said laminae and surfaces of said elements which are appositioned to said pair of outer laminae.

4. In a composite building unit all parts of which are adapted to be readily severable, the combination of a pair of hard and rigid boards each having a side appositioned in spaced relation to a side of the other, said boards being adapted to resist compression and tension stresses, a somewhat compressible and comparatively soft core interposed between said boards, said core being incapable of resisting shear stresses, reinforcing stitching through said core with distributed sections of the stitching extending along each appositioned side of the core and means for securing the boards to opposite sides of the core respectively and also to the said sections of the stitching.

5. A laminated structure comprising a. core of loosely compacted fibrous material, exible nonmetallic stitching through said core and cover boards of closely compacted ilbrous material cemented to opposite sides respectively of said core and also to exposed sections of said stitching, said boards being inherently sufliciently strong to resist compression and tension stresses respectively, said stitched core being adapted to resist horizontal shear stresses.

6. In rigid laminated structure capable oi sustaining loads when freely supported, the combination of a core of loosely compacted tlbrous material provided with a plurality of reinforcing units each extending from one side of said core to the opposite side thereof and adapted individually and collectively to resist horizontal shear and a pair of cover boards of closely compacted fibrous material adapted to resist compression and tension stresses respectively and secured to the opposite sides of said core and to said reinforcing units, said structure comprehending the principle of an I-beam in which the reinforced core corresponds with the web of such beam and the cover boards correspond with the flanges of such beam,

7. In a rigid laminated structural unit capable of sustaining loads when freely supported, the

combination of a core of loosely compacted fibrous material provided with fibre stitching extending from one side of the core to its opposite side and purposed to resist horizontal shear, and a pair of cover boards of closely compacted fibrous material respectively purposed to resist compression and tension stresses and secured to the opposite sides of said core respectively and to said coreexternal return bend sections of said stitching, said structural unit comprehending the principle of an I-beam in which the stitched core corresponds with the web of such a beam and in which the cover boards correspond with the flanges of such a beam, opposite edges of the composite unit being formed one as a tongue and the other as a groove to permit interlocking of adjoining units.

8. A rigid laminated structural unit capable of sustaining loads when freely supported, said unit comprising a core of loosely compacted brous material and cover boards of closely compacted and rigid brous material, said unit corresponding generally to an I-beam in which the core is the equivalent of its web and the cover boards are the equivalent of its anges, said core in unreinforced condition being insuilciently strong in shear resistance fully to develop the ange strength inherent in said cover boards, reinforcing stitching extending back and forth through said core and adapted to resist horizontal shear and to develop in said core the maximum flange strength of said cover boards.

9. A rigid, laminated structural unit capable of sustaining loads when freely supporting said unit comprising a dry, compressible core of loosely compacted fibrous material of predetermined thickness, and cover boards of closely compacted and rigid fibrous material of less thickness than said core yet adapted to resist compression and tension stresses, said unit corresponding generally to an I-beam.in which the core corresponds with the web of such a beam and in which the cover boards correspond with the flanges of such a beam, said core, in its unreinforced condition being insufficiently strong in its resistance to horizontal shear fully to develop the ange strength inherent in said cover boards, a non-metallic readily sawed reinforcing stitching through said core and purposed to resist horizontal shear and to develop the maximum ange strength of said cover boards and cementation means for uniting both core and stitching with said boards.

10. A structure of the character described comprising three severable laminae of which the separated pair are adequately hard and rigid for withstanding expectable compression and tension stresses and of which the interjacent one is of light weight insulating material inherently incapable of adequate shear resistance and severable stitching extending entirely through and progressing transversely across saidinterjacent lamina to reinforce it against shear stress whereby to produce a building unit having elements adapted to exercise a function equivalent to that of the anges of an I-beam and having an inter- Jacent connecting element adapted to exercise a. Iiaeunction equivalent to that oi the web of an I- am.

ARMEN H. TABHJIAN. 

